A review of the formation law and catastrophic evolution mechanism of giant landslides in complex engineering geological conditions in the western alpine valley area, China

[Objective] Most hydroelectric projects in Western China are situated in alpine canyons. The intricate engineering geological conditions in this area contribute to the widespread distribution of landslide disasters on the reservoir banks of hydroelectric projects. [Methods] Based on the engineering geological characteristics of the western alpine canyons, the correlation between topography, geological structure, landslide material, slope structure, hydrogeological conditions, and the formation and progression of landslides is analyzed. It also delineates the types and features of landslide development in the western region and the mechanical mechanisms governing the evolution of typical landslide disasters. [Results] The results indicate that the landslides are characterized with slopes ranging from 30° to 50°, elevations exceeding 1000 m, and volumes surpassing one million cubic meters. Triassic, Ordovician, and Silurian strata are identified as the principal slippery strata in this area. Rainfall and reservoir impoundment significantly influence landslide stability, leading to erosion datum uplift and range expansion. Fluctuations in water levels result in diminished rock and soil properties along the leading edge of advancing landslides. [Conclusion] The most frequent landslides in the western alpine region include accumulation landslides dominated by traction, thrust, and composite mechanisms, as well as rock landslides dominated by bedding, buckling, anti-dip, and seating mechanisms. [Significance] The study elucidates landslide disaster mechanisms under varying evolutionary and failure mechanical processes, providing a significant guidance value for the identification, monitoring, early warning and prevention of landslide disasters in the western region.